I built a “Sumicom S600”:http://www.itreviews.co.uk/hardware/h419.htm a while back and Grace uses it now. It has worked pretty well. The main issues have been that it is still quite noisy even with the tunable fan I installed and it runs very hot even with a relatively low power Pentium 4 2.53 processor.
The latest incarnation is the S625 which uses a more modern Northwood with 800MHz FSB. Also, it is VGA only so image quality on monitors is just OK. The most interesting model uses the Pentium M and the 855 chipset so it should be super cool and fast. That’s probably the model to get.
Its so small you don’t have anything but onboard graphics, so gamers don’t need to apply as “trustedreviews.com”:http://www.trustedreviews.com/article.aspx?art=42 notes.
There are now smaller models out there like the cappuccinopc.com : mocha mini pc series 5043 / 7042 and also check out “Logic supply”:http://logicsupply.com
Still it is a nice little machine that assembles OK. It uses notebook sized SODIMM and a slimline notebook size DVD, but otherwise it is just find.